Adhesive including medicament and device and method for applying same

ABSTRACT

The present invention provides a device and method for safely applying cyanoacrylate or other adhesives to skin lacerations.

This application is a continuation of application Ser. No. 10/032,225,filed Dec. 18, 2001, which claims priority under 35 U.S.C. § 119(e) tothe following U.S. provisional applications: Application No. 60/306,572,filed Jul. 19, 2001; Application No. 60/308,993, filed Jul. 31, 2001;Application No. 60/337,662; filed Nov. 7, 2001; and Application No.60/341,598, filed Dec. 17, 2001, the disclosures of which are herebyincorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention provides a device and method for safely applyingcyanoacrylate or other adhesives to skin lacerations.

BACKGROUND OF THE INVENTION

Wound closure technology continues to evolve with non-suturealternatives such as staples, surgical tapes, and most recently, tissueadhesives, which have rapidly gained recognition and acceptance aseffective wound closure methods. Two different forms of tissue adhesivesfor wound closure have been extensively studied: cyanoacrylate tissueadhesives and fibrin sealants. Fibrin sealants have not gainedacceptance because of the low tensile strength of the fibrin polymer,lengthy preparation time, and the risk of viral transmission. Thecyanoacrylates are recognized as superior adhesives for skin woundclosure and are undergoing continuous modification to improve thetechnology.

A common property of all of the cyanoacrylates is the ability to bondand polymerize in the presence of water and to form a bond between thetwo sides of a wound to hold it in position. When used for woundclosure, the cyanoacrylate polymerizes in the presence of watermolecules on the skin surface, forming a bridge and bond that keeps thetissue together for the purpose of wound healing. The polymerizedmaterial then progressively and slowly flakes off after holding the skintissues in that position. The difficulties and hazards associated withthe use of cyanoacrylates are well known. Entry of cyanoacrylates intothe wound promotes infection and a foreign body reaction. Thecyanoacrylates are toxic and there may be adverse reactions because ofhypersensitivity to cyanoacrylates themselves or formaldehyde, one ofthe starting materials used for preparing cyanoacrylate adhesives.

The first cyanoacrylates used as tissue adhesives included the shortchain cyanoacrylates, commonly referred to as Super Glues™, wereassociated with severe acute and chronic inflammatory reactions.Subsequently, longer chain cyanoacrylates, including butyl and octylcyanoacrylates have gained acceptance. While butyl cyanoacrylatesprovide effective closure of simple superficial lacerations andincisions, they are toxic when introduced into vascular areas andexhibit low tensile strength and high brittleness.

Octyl cyanoacrylates have proved to be superior adhesives for woundclosure, demonstrating greater tensile strength than the butylcyanoacrylates, and are remarkably nontoxic when used for skin woundclosure, but may be toxic if allowed to enter the wound. Octylcyanoacrylate has been approved by the FDA for use as a tissue adhesive.However, there are problems associated with its use, including a higherincidence of wound infection when compared to suturing as a woundclosure method. Also, blood and body fluids trigger prematurepolymerization of the cyanoacrylate, resulting in an unsightlyplasticized mass with very little skin bonding. It is also difficult tokeep adhesive out of the wound. The polymerization reaction isexothermic, and the generated heat can result in patient discomfort.Octyl cyanoacrylates may have a low viscosity, causing them to run intoundesirable areas or into the wound. For example, cyanoacrylates runninginto the eye can result in tarsorrhaphy (lid fusion) or corneal injury.

SUMMARY OF THE INVENTION

There is a need in the art of wound closure for a device and a method ofapplying an adhesive with greater ease and with improved wound healingand to prevent the adhesive from running into the wound or inadvertentlyinto the eye, nose, mouth, or other areas.

In a first embodiment, a wound approximation device is provided, thedevice including a resilient sheet and an opening, wherein the openingis of a sufficient size such that it surrounds a skin wound and exposesa margin of skin surrounding the wound when the resilient sheet in astretched form is placed against the skin, and wherein a portion of theresilient sheet adjacent to the opening and opposite to a side of theresilient sheet to be placed against the skin includes a substance whichdoes not form a strong bond with a wound-sealing adhesive used to sealthe wound.

In various aspects of the first embodiment, the resilient sheet includesan elastomer, a vinyl sheet, or a urethane sheet. The portion of theresilient sheet adjacent to the opening and opposite to a side of theresilient sheet to be placed against the skin may include a vinyl, or aurethane. The portion of the resilient sheet to be placed against theskin may include a backing adhesive, for example, a pressure sensitiveadhesive, such as a butyl acrylate. The wound sealing adhesive mayinclude a cyanoacrylate.

In a second embodiment, a method of sealing a wound is provided, themethod including the steps of: providing a wound approximation device,the device including a resilient sheet and an opening; applying tensionto the resilient sheet whereby the opening is enlarged to a sufficientsize such that it may surround a skin wound and expose a margin of skinsurrounding the wound; pressing the resilient sheet under tensionagainst the skin to form a bond to the skin, such that the openingsurrounds the skin wound and exposes a margin of skin surrounding thewound; and releasing the tension in the resilient sheet, whereby thewound is approximated.

In various aspects of the second embodiment, the method may furtherinclude the step of debriding the approximated wound, irrigating theapproximated wound, disinfecting the approximated wound, or sealing theapproximated wound. When the method includes the further step of sealingthe approximated wound, the step may include suturing the approximatedwound, stapling the approximated wound, or applying a wound sealingadhesive to the approximated wound.

In another aspect of the second embodiment, the method further includesthe step of removing the wound approximation device from the skin,wherein said step is conducted after the step of sealing theapproximated wound. The resilient sheet may include a urethane sheet,and the step of sealing the approximated wound may include applying acyanoacrylate adhesive to the approximated wound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a diagram depicting a skin wound laceration and theposition of a tissue adhesive with respect to the various layers of theskin, including the stratum corneum, cellular layer, thick collagenlayer, and subcutaneous fat.

FIG. 2 provides a diagram depicting how an adhesive typically sloughsoff with the outermost layer of the stratum corneum.

FIG. 3 provides illustrations depicting the use of the woundapproximation device. FIG. 3 a illustrates a wound. FIG. 3 b illustratesthe device when stretched under tension to enlarge the opening. FIG. 3 cillustrates the device after application of the stretched device to thewound and release of tension, whereby the wound is approximated. FIG. 3d illustrates the device after application of an adhesive to theapproximated wound.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Introduction

The following description and examples illustrate a preferred embodimentof the present invention in detail. Those of skill in the art willrecognize that there are numerous variations and modifications of thisinvention that are encompassed by its scope. Accordingly, thedescription of a preferred embodiment should not be deemed to limit thescope of the present invention.

Minimally Invasive Surgery (MIS) surgery has lessened suffering ofpatients. Medical cyanoacrylate adhesives have been successfully usedfor effectively sealing the wounds acquired during such surgery, as wellas for sealing other wounds such as lacerations.

A device is provided for use in applying an adhesive, for example, acyanoacrylate medical adhesive, to skin in order to seal a wound orlaceration. The device includes a sheet of resilient material providedwith an opening. The opening is typically in the form of a slit in theresilient material, although in certain embodiments the opening may takea different form, e.g., a circle, rectangle or square, elipse,lens-shape, or the like. The sheet may be stretched, applied to the areaof skin surrounding the wound, then the tension released, therebyapproximating the wound. An adhesive is then applied to the approximatedwound. The surfaces of the sheet material surrounding the wound on theside of the sheet opposite the skin preferably include a material thatdoes not form a strong bond with the adhesive, so as to facilitateremoval of the sheet after application of the adhesive.

Cyanoacrylate Adhesives

The adhesives of the preferred embodiments include polymers of2-cyanoacrylic esters, more commonly referred to as cyanoacrylates.Cyanoacrylates are hard glass resins that exhibit excellent adhesion tohigh energy surfaces, such as skin, but do not form strong bonds withlow energy materials, e.g., polyolefins, polytetrafluoroethylene(marketed under the name Teflon™), and polyvinylchloride (commonlyreferred to as vinyl). Cyanoacrylate polymers are spontaneously formedwhen their liquid monomers are placed between two closely fittingsurfaces. The excellent adhesive properties of cyanoacrylate polymersarises from the electron-withdrawing characteristics of the groupsadjacent to the polymerizable double bond, which accounts for both theextremely high reactivity or cure rate, and their polar nature, whichenables the polymers to adhere tenaciously to many diverse substrates.

Cyanoacrylate Monomer Chemistry

Some of the more common cyanoacrylate monomers include, but are notlimited to, the ethyl, methyl, isopropyl, allyl, n-butyl, isobutyl,methoxyethyl, ethoxyethyl, and octyl esters. Cyanoacrylate adhesives aremanufactured and marketed worldwide by various companies includingLoctite, a Henkel Company, of Rocky Hill, Conn., SAFE-T-LOCInternational Corporation of Lombard, Ill., SUR-LOK Corporation ofWalworth, Wis., and Elmers Products, of Columbus, Ohio, the manufacturerof the well-known Krazy Glue™. The ability of cyanoacrylates to rapidlycure and bond to skin makes them particularly well suited for use asmedical adhesives. Cyanoacrylate adhesives suitable for use as medicaladhesives include octyl 2-cyanoacrylate marketed as Dermabond™ topicalskin adhesive by Ethicon, Inc., a Johnson & Johnson Company, ofSomerville, N.J., and butyl cyanoacrylate marketed as Vetbond™ by WorldPrecision Instruments, Inc. of Sarasota, Fla.

The 2-cyanoacrylic ester monomers are all thin, water-clear liquids withviscosities of 1-3 mPa. Only a few of the many esters that have beenprepared and characterized are of any significant commercial interest.Methyl and ethyl cyanoacrylates are most commonly used for industrialadhesives. Cyanoacrylate adhesives for medical and veterinary usegenerally include the longer alkyl chain cyanoacryates, including thebutyl and octyl esters.

The base monomers are generally too thin for convenient use andtherefore are generally formulated with stabilizers, thickeners, andproperty-modifying additives. The viscosities of such cyanoacrylateadhesives can range from that of the base monomer to thixotropic gels.The alkyl esters are characterized by sharp, lacrimatory, faintly sweetodors, while alkoxyalkyl esters are nearly odor free, but less effectiveadhesives.

Bond Formation

Cyanoacrylate liquid monomers polymerize nearly instantaneously via ananionic mechanism when brought into contact with any weakly basic oralkali surface. Even the presence of a weakly basic substance such asadsorbed surface moisture is adequate to initiate the curing reaction.The curing reaction proceeds until all available monomer has reacted oruntil it is terminated by an acidic species. The time of fixture forcyanoacrylate occurs within several seconds on strongly catalyticsurfaces such as skin to several minutes on noncatalytic surfaces.Surface accelerators or additives enhancing the curing rate may be usedto decrease the time of fixture on noncatalytic surfaces. However, suchaccelerators and additives are generally not preferred for use inbonding skin due to the catalytic nature of the skin surface. The basicpolymerization reaction includes the following initiation, propagation,and termination steps:

Cyanoacrylate Adhesive Formulations

Cyanoacrylate adhesives are soluble in N-methylpyrrolidone,N,N-dimethylformamide, and nitromethane. Cured cyanoacrylates are hard,clear, and glassy thermoplastic resins with high tensile strengths, buttend to be brittle and have only low to moderate impact and peelstrengths. Elastomeric materials may be dissolved in cyanoacrylateadhesive formulations to yield a cured adhesive of greater flexibilityand toughness. The longer alkyl chain esters generally have longer curerates, reduced tensile and tensile shear strength and hardness comparedto the shorter alkyl chain esters. The longer alkyl chain esters alsoexhibit reduced glass-transition temperatures (T_(g)) and adhesive bondservice temperature when compared to the shorter alkyl chain esters.

Although the alkyl cyanoacrylate esters are the most commoncyanoacrylate adhesives, in certain embodiments it may be preferred touse a cyanoacrylate ester adhesive other than an alkyl ester. Forexample, allyl esters, which may cross-link by a free-radical mechanismthrough the allyl group, may be used in applications wherein increasedthermal resistance is desirable. Alkoxyalkyl esters may be used in thoseapplications where reduced odor is desirable and wherein a slightlyreduced adhesive performance is acceptable.

Cyanoacrylate adhesives are prepared via the Knoevenagel condensationreaction, in which the corresponding alkyl cyanoacetate reacts withformaldehyde in the presence of a basic catalyst to form a low molecularweight polymer. The polymer slurry is acidified and the water isremoved. The polymer is cracked and redistilled at a high temperatureinto a suitable stabilizer combination to prevent prematurerepolymerization. Strong protonic or Lewis acids are normally used incombination with small amounts of a free-radical stabilizer.

Adhesives formulated from the 2-cyanoacrylic esters typically containstabilizers and thickeners, and may also contain tougheners, colorants,and other special property-enhancing additives. Both anionic andfree-radical stabilizers are required, since the monomer will polymerizevia both mechanisms. Although the anionic polymerization mechanismdepicted above is the predominant reaction, the monomer will undergofree radical polymerization under prolonged exposure to heat or light.To extend the usable shelf life of cyanoacrylate adhesive formulations,free-radical stabilizers such as quinones or hindered phenols arecommonly added to the formulations. Anionic inhibitors such as nitricoxide may also be added. Such anionic inhibitors alter the viscosity andpolymerization rate, thereby minimizing the risk of inadvertent spillageand facilitating application.

Both the liquid and cured cyanoacrylates support combustion, and highlyexothermic polymerization can occur from direct addition of catalyticsubstances such as water, alcohols, and bases such as amines, ammonia,or caustics, or from contamination with surface activators.

Cyanoacrylate Adhesives for Medical Uses

Cyanoacrylate adhesives will rapidly bond to skin because of thepresence of moisture and protein in the skin. Octyl cyanoacrylates arethe most widely used cyanoacrylate adhesive for tissue sealing. Whenbonding to tissue, octyl cyanoacrylates are four times stronger and lesstoxic than butyl cyanoacrylate. However, butyl cyanoacrylate issometimes preferred for sealing deeper lacerations because it breaksdown more easily and can be absorbed by the tissue more quickly thanoctyl cyanoacrylate.

The 2-cyanoacrylic esters have sharp, pungent odors and are lacrimators,even at very low concentrations. These esters can be irritating to thenose, throat, and eye at concentrations as low as 3 ppm. Goodventilation when using the adhesives is essential, and contact with theeye or other sensitive body parts is to be avoided when usingcyanoacrylate adhesives for wound sealing. The cured 2-cyanoacrylicester polymers are relatively nontoxic, making them suitable for medicaluse. While mild skin irritation may be observed, there is no evidence ofsensitization or absorption of the cyanoacrylate adhesives through theskin.

Wound Approximation Device and Method for Sealing Skin Wounds

Cyanoacrylate adhesives, or other medical adhesives as are known in theart, may be used in conjunction with a tissue closure device thatexpediently allows a firm approximation of skin wound edges and preventsbody fluids (e.g., tears, sweat, blood) from contaminating the wound.The device includes a stretched sheet with one side adherent to the skinthat is applied to surround the laceration. When applied in a stretchedstate then the tension released, the device controls about the wound,thus holding the wound edges together. The sheet forms a dam thatprevents body fluids from contaminating the wound and also prevents thecyanoacrylate adhesive from entering critical structures adjacent to thewound, e.g., the eye, nose, or mouth.

A device to gain wound approximation and insulation from contaminationor inadvertent spread of adhesive agents is provided. The woundapproximation device includes a resilient material provided with anopening. The opening is of suitable size and shape such that when theresilient material is stretched under tension and positioned on theskin, the opening surrounds the wound to be approximated. After theresilient material is placed on the skin such that the opening surroundsthe wound to be approximated, the tension is released and the resilientmaterial contracts. When the resilient material contracts, the wound isapproximated. After approximation is achieved, the wound may be subjectto treatment, including, but not limited to debridement, irrigation,disinfection, wound sealing or closing, and the like. Closing the woundmay be accomplished by use of adhesives, suturing, stapling, lasertissue welding, or other accepted procedures known to those of skill inthe art.

Resilient Material

The wound approximation device of preferred embodiments includes anelastic sheet, a stretchable woven or nonwoven fabric, or any othersuitable resilient material that may be stretched then draped around thewound. Suitable resilient materials are preferably stretchable in anydirection. However, in certain embodiments it may be preferred oracceptable to use a resilient material that is stretchable in only onedirection, e.g., longitudinally stretchable. Suitable resilientmaterials are generally capable of a measured maximum extension of atleast about 30% of their relaxed length, preferably at least about 40%or 50% of their relaxed length, more preferably at least about 60%, 70%,80%, or 90% of their relaxed length, and most preferably at least about100%, 150%, 200%, 250%, 300%, 400%, 500% or more of their relaxedlength. However, in certain embodiments it may be desirable to use amaterial capable of a measured maximum extension of less than about 30%of its relaxed length.

In preferred embodiments, the resilient material includes one or moresheets of elastomers. Elastomers are polymers possessing elasticproperties. Preferred elastomers include, but are not limited to,natural and synthetic rubbers such as styrene-butadiene rubbers, butylrubbers, acrylonitrile-butadiene rubbers, polysulfide rubbers, latex,neoprene, polyurethanes, polyacrylate elastomers, silicone elastomers,fluoroelastomers, polyolefins such as ethylene-propylene elastomers, andpolyvinyl chlorides. A single elastomer may be used, or a mixture orcombination of two or more elastomers may be used. In general, it ispreferred that the elastomeric material exhibit an elongation of about100% at 2,800 psi (19.3 MPa). However, in certain embodiments anelastomeric material exhibiting 100% elongation at greater than or lessthan 2,800 psi may be preferred.

Other suitable elastic materials include resilient stretchable fabrics.Such fabrics may include woven or nonwoven fibers of the elastomericmaterials described above. An example of a suitable fiber that may beused in resilient stretchable fabrics is Lycra™ a stretchy fiber madefrom lightweight polyurethane. Lycra™ is available from DuPont Corp. ofWilmington, Del.

While solid sheets of elastomeric material are generally preferred, incertain embodiments it may be preferred to use a sheet other than asolid sheet, e.g., a perforated sheet. A perforated sheet may bepreferred for applications wherein the wound approximation device isleft in place on the skin for an extended period of time, theperforations permitting air circulation to the skin under theperforations.

In preferred embodiments, the elastic material comprisespolyvinylchloride (commonly referred to as vinyl) or polyurethanesheeting. A polyurethane material suitable for use in preferredembodiments is marketed under the tradename DuBan® Cohesive ElasticBandage by Dumex U.S.A. of Marietta, Ga. DuBan is a latex-free cohesiveelastic bandage that adheres to itself, but not to the skin or hair. Itconforms to body contours while offering controlled compression, and islightweight and water resistant.

Other materials that may be suitable for use in various preferredembodiments are commercially available from CT Biomaterials, a Divisionof CardioTech International, Inc. of Wyburn, Mass. These materials aremarketed under the tradenames ChronoFlex® C, ChronoFlex® AR,ChronoThane® P, and ChronoPrene™.

ChronoFlex® C is a family of polycarbonate aromatic biodurablethermoplastic polyurethane elastomers developed by CT Biomaterials, aDivision of CardioTech International, Inc. of Wyburn, Mass. Typicalproperties for ChronoFlex® C materials having various hardnesses isprovided in Table 1 below. TABLE 1 Physical Properties of ChronoFlex ® CPolymers ASTM Properties Procedure Typical Values Hardness (ShoreDurometer) ASTM D-2240 80A 55D 75D Appearance Visual Clear to Clear toClear to slightly slightly slightly cloudy cloudy cloudy UltimateTensile Strength (psi) ASTM D-638 5500-6500 6000-7500 7000-8000 UltimateTensile Strain (%) ASTM D-638 400-490 365-440 255-320 100% SecantModulus (psi) ASTM D-638  770-1250 1850-2200 5300-5700 300% SecantModulus (psi) ASTM D-638  700-1400 1700-2000 2700-3200 Flexural Strength(psi) ASTM D-790 350 550 10,000 Flexural Modulus (psi) AS′TM D-790 55009300 300,000 Melt Index (g/10 min) 210° C.; 2.17 Kg ASTM D-1238 8 5 3Vicat Softening Point (° F./° C.) ASTM D-1525 160/70 180/80 — WaterAbsorption ASTM D-5170 1.2 1.0 0.8 Dielectric Strength (volts/Mil) ASTMD-149 360 520 420 Specific Gravity ASTM D-792 1.2 1.2 1.2 Coefficient ofFriction (Kinetic) ASTM D-1894 1.5 0.8 0.64 Abrasion Resistance (% lossat 1000 cycles) ASTM D-1044 0.008 0.035 0.053 Melt Process. Temp. (°F./° C.) 375-430/190-220 Recommended Sterilization Method Gamma; E-Beam;ethylene oxide Class VI Biocompatibility Test U.S.P. XXII Pass Pass Pass

ChronoFlex® AR is a solution-grade, segmented, aromatic,polycarbonate-based polyurethane elastomer. Films prepared fromChronoFlex® AR pass or exceed all requirements specified in the USPClass VI biocompatibility tests. Typical physical properties ofChronoFlex® AR films are provided in Table 2 below. TABLE 2 PhysicalProperties of ChronoFlex ® AR Polymers Durometer, (Shore) ASTM D-2240 75A Tensile Strength ASTM D-412 7500 psi Elongation ASTM D-412 500%

ChronoThane™ P is a family of aromatic ether-based polyurethaneelastomers. It has a low coefficient of friction, low extractables,dimensional stability, gama sterilizable, chemical inertness, andbiodurability, and easy thermoplastic processibility. Typical physicalproperties of ChronoThane P-80 A are provided in Table 3 below. TABLE 3Physical Properties of ChronoThane ® P Polymers Durometer (Shore) ASTMD-2240 80A Tensile Strength ASTM D-412  5100 psi Elongation ASTM D-412 550% Modulus @ 100% Elongation  850 psi Modulus @300% Elongation  1750psi Tear Strength Die “C” ASTM D-624  420 pli Vicat Softening ASTMD-1525  185° F. Flexural Modulus ASTM D-790 15000 psi

ChronoPrene™ is based on styrenic olefinic rubber and hydrogenatedisoprene. ChronoPrene™ contains polypropylene as a reinforcing agent andmineral oil as a plasticizer and processing aid. Physical properties ofChronoPrene™ Polymers are provided in Table 4 below. TABLE 4 PhysicalProperties of ChronoPrene ™ Polymers Hardness-Shore ASTM D2240 (3 sec.)25A 40A Specific Gravity 0.87 0.90 Tensile Strength (psi) (ASTM D412)600 700 Elongation (ASTM D412) 600% 500% Color Translucent Translucent

While vinyl or polyurethane sheeting is preferred for certainembodiments, other suitable elastic material may preferred for otherembodiments. Such elastic materials are well known in the art.

The wound approximation device may include a single layer of resilientmaterial, or two or more layers of resilient material bonded together.The layers of resilient material may include the same material, forexample, multiple layers of vinyl sheeting. Such a configurationprovides flexibility in preparing wound approximation devices of a widerange of thicknesses using a single thickness of sheeting as a startingmaterial. Alternatively, the resilient material may include twodifferent materials, for example, a layer of vinyl sheeting bonded to astretchable woven or nonwoven fabric. Such a configuration may lendgreater structural integrity to the resilient material, therebypreventing or minimizing inadvertent enlarging of the opening by tearingwhen tension is applied to the wound approximation device.

The resilient material may be provided with one or more coatings, ifdesired. Such coatings may assist in forming a bond between the skin andthe wound approximation device, or may prevent undesired adhesion ofmaterials, e.g., adhesives, to the wound approximation device.

Pressure Sensitive Adhesive

To ensure that the skin surrounding the wound remains affixed to theresilient material after the stretching of the resilient material isrelaxed, it is preferred that the side of the resilient materialadjacent to the skin incorporates a suitable adhesive. Although anyadhesive suitable for forming a bond with skin may be used, it isgenerally preferred to use a pressure sensitive adhesive. Pressuresensitive adhesives are generally defined as adhesives that adhere to asubstrate when a light pressure is applied but leave no residue whenremoved. Pressure sensitive adhesives include, but are not limited to,solvent in solution adhesives, hot melt adhesives, aqueous emulsionadhesives, calenderable adhesive, and radiation curable adhesives.Solution adhesives are preferred for most uses because of their ease ofapplication and versatility. Hot melt adhesives are typically based onresin-tackified block copolymers. Aqueous emulsion adhesives includethose prepared using acrylic copolymers, butadiene styrene copolymers,and natural rubber latex. Radiation curable adhesives typically consistof acrylic oligomers and monomers, which cure to form a pressuresensitive adhesive upon exposure to ultraviolet lights.

The most commonly used elastomers in pressure sensitive adhesivesinclude natural rubbers, styrene-butadiene latexes, polyisobutylene,butyl rubbers, acrylics, and silicones. In preferred embodiments,acrylic polymer or silicone based pressure sensitive adhesives are used.Acrylic polymers generally have a low level of allergenicity, arecleanly removable from skin, possess a low odor, and exhibit low ratesof mechanical and chemical irritation. Medical grade silicone pressuresensitive adhesives are preferred for their biocompatibility.

Amongst the factors that influence the suitability for a pressuresensitive adhesive for use in the wound sealing devices of preferredembodiments are the absence of skin irritating components, sufficientcohesive strength such that the adhesive may be cleanly removed from theskin, ability to accommodate skin movement without excessive mechanicalskin irritation, and good resistance to body fluids.

In preferred embodiments, the pressure sensitive adhesive comprises abutyl acrylate. Such adhesives are used as the pressure sensitiveadhesive in the DuBan® Cohesive Elastic Bandage described above. Whilebutyl acrylate pressure sensitive adhesives are generally preferred formany application, any pressure sensitive adhesive suitable for bondingskin may be used. Such pressure sensitive adhesives are well known inthe art.

In certain embodiments, the portion of the wound sealing device incontact with skin may form a sufficient bond (for example, by friction)with the skin such that an adhesive, such as a pressure sensitiveadhesive, is not necessary. However, for ease of use and to ensure thatthe skin remains in fixed position after the stretching is relaxed, itis generally preferred that a pressure sensitive adhesive is used.

Low Surface Energy Coating

In certain embodiments, the wound approximation device may be used toapproximate a wound prior to closing the wound using an adhesive, forexample, a cyanoacrylate adhesive. In such applications, it is desirablethat the cyanoacrylate or other adhesive adheres only to the skin, andnot to the wound approximation device so that the wound approximationdevice may be easily removed from the skin after the wound is closed.

Cyanoacrylate adhesives do not achieve very high bond strength on lowsurface energy polymers. Surface energy is a relative phenomenon, so togauge the effects of surface energy on adhesion, the surface energy of aliquid must be compared to that of a solid surface. A liquid possessinga lower surface energy than the solid surface will spontaneously wet outthe solid surface. Conversely, a liquid possessing a higher surfaceenergy than the solid surface will bead up on the surface instead ofwetting out. Wet out generally refers to how well a liquid flows andintimately covers a surface. Maximum adhesion develops when the adhesivethoroughly wets out the surface to be bonded. The greater the wet out,the better the surface coverage and the greater the attractive forcesbetween the adhesive and the solid surface. Surfaces with low surfaceenergy do not readily form bonds because they are more difficult to wetwith the adhesive.

Polymers having a low surface energy when compared to cyanoacrylateadhesives are well known in the art, and include, for example, vinyls,polyolefins, fluoropolymers, and certain silicones. Low surface energypolymers suitable for use in preferred embodiments include, but are notlimited to, polyvinylchloride, polypropylene, polyethylene,polytetrafluoroethylene.

In preferred embodiments wherein the wound approximation device is usedin conjunction with a cyanoacrylate adhesive, the resilient material ismade up of a low surface energy polymer. Alternatively, a portion of theresilient material adjacent to the opening surrounding the wound may becoated with a low surface energy material. In other embodiments, one ormore surfaces of the resilient material are completely coated with a lowsurface energy material. Alternatively, a composite including two ormore layers of different materials may be prepared, wherein one of thelayers is the resilient material and another layer is a low surfaceenergy material. The two layers may then be bonded using any suitablemethod, e.g., adhesives such as pressure sensitive adhesives, hot meltadhesives, curable adhesives, application of heat or pressure such as inlamination, physical attachment through the use of stitching, studs, orother fasteners, and the like.

When the resilient material is a sheet of a low surface energy material,such as vinyl, and a pressure sensitive adhesive is used to adhere thewound approximation device to the skin, it may be desirable to subjectthe surface of the sheet bearing the pressure sensitive adhesive to apretreatment or priming prior to application of the pressure sensitiveadhesive so as to improve the bonding of the pressure sensitive adhesiveto the sheet. Alternatively, a pressure sensitive adhesive specificallyformulated for use with a low surface energy material may be selected.Certain acrylic-based pressure sensitive adhesives are especiallypreferred for use with low surface energy materials.

Other coatings may be preferred if adhesives other than cyanoacrylatesare used. When such other adhesives are used, a coating or an uncoatedsheet should be selected such that the adhesive does not form a strongbond with the sheet.

The Opening

The wound approximation device is provided with at least one opening. Awound approximation device may be provided with an opening preformed.Alternatively, the opening may be formed in the continuous sheet priorto use in view of the wound to be sealed, the size and the shape of theopening configured to match that of the wound. In certain embodiments,it may be desirable to include more than one opening. For example, twowounds adjacent to each other may be closed simultaneously using a woundapproximation device having two openings. Alternatively, if the wound isparticularly long, it may be desirable to have a series of openingsseparated by small bridges of the material of the sheet, or a largeropening wherein opposite sides of the opening are secured together at aseries of points along the opening, e.g., by stitching or appropriatefasteners. Such a configuration may enable the center portion of a longwound to be better approximated than if a long, unbroken opening isprovided. The maximum size of an opening that provides satisfactorywound approximation may differ depending upon the nature of theresilient material used. Certain resilient materials may be preferredfor closing small wounds, whereas other materials may be preferred forapproximating larger wounds. Vinyl sheeting is generally preferred asproviding satisfactory results for a wide range of wound sizes. Thewound approximation device is preferably used to approximate wounds upto about 3 to 4 cm in length. However, in certain embodiments the woundapproximation device may be used to approximate wounds longer than about3 to 4 cm.

The Wound Approximation Device

The wound approximation device may be provided in the form of a sheet ofpreselected size. Alternatively, a larger sheet of material may be cutor trimmed to provide a wound approximation device of a size and shapeappropriate to the wound. The wound approximation device is typicallyremoved from the skin after approximation and sealing of the wound.However, in certain embodiments it may be preferred to leave the woundapproximation device in place for an extended period of time. In suchapplications, it may be preferred to select a pressure sensitiveadhesive appropriate for extended contact with the skin, or to includean appropriate medicament, e.g., an antibiotic, an anti-inflammatorycomposition, or an anesthetic, in the pressure sensitive adhesive.

Wound Approximation and Closure with a Cyanoacrylate Adhesive

In a preferred embodiment, the wound approximation device is used toapproximate a wound prior to sealing it with a cyanoacrylate adhesive.Illustrated in FIG. 1 is a skin wound laceration and the position of atissue adhesive with respect to the various layers of the skin,including the stratum corneum, cellular layer, thick collagen layer, andsubcutaneous fat. The tissue adhesive bonds to the outer cornified layerof skin. Tissue bonding occurs at site A—the interface between thetissue adhesive and the stratum corneum. FIG. 2 illustrates how theadhesive typically sloughs off with the outermost layer of the stratumcorneum, generally from 1-2 weeks after application of the adhesive.

To ensure rapid healing, it is preferred that the adhesive not enterinto the wound itself. To minimize entry of the adhesive into the wound,the wound is approximated using the wound approximation device prior toapplication of the cyanoacrylate adhesive to the wound. FIG. 3 depictsuse of the wound approximation device of a preferred embodiment forsealing a wound. FIG. 3 a illustrates a laceration approximately 2.5 cmin length on the inner thigh of a pig. FIG. 3 b illustrates a woundapproximation device of a preferred embodiment, wherein the deviceincludes a DuBan DuBan® Cohesive Elastic Bandage provided with anopening, wherein the side of the bandage to be placed adjacent to theskin is provided with a butyl acrylate pressure sensitive adhesive Thesheet is stretched under tension to enlarge the opening, as illustratedin FIG. 3 b. Any suitable method may be used to apply the tension, e.g.,grasping the edges and pulling them apart, or securing the woundapproximation device to an apparatus capable of applying tension to thesheet. The sheet is then pressed to the skin such that the wound iscentered in the opening and such that a bond is formed between thepressure sensitive adhesive and the skin. The tension is then released,and the vinyl sheet contracts to approximate the wound, as shown in FIG.3 c. The wound is then sealed by applying a cyanoacrylate adhesive tothe skin exposed by the opening, as shown in FIG. 3 d. Because vinyl isa low surface energy material when compared to cyanoacrylate, thecyanoacrylate bonds to the skin but does not form an effective bond tothe vinyl sheeting. Therefore, after the cyanoacrylate cures, the vinylsheet may be removed from the skin without substantially disturbing thebond between the cyanoacrylate and the skin.

The above description discloses several methods and materials of thepresent invention. This invention is susceptible to modifications in themethods and materials, as well as alterations in the fabrication methodsand equipment. Such modifications will become apparent to those skilledin the art from a consideration of this disclosure or practice of theinvention disclosed herein. Consequently, it is not intended that thisinvention be limited to the specific embodiments disclosed herein, butthat it cover all modifications and alternatives coming within the truescope and spirit of the invention as embodied in the attached claims.

Every reference mentioned herein is hereby incorporated by reference inits entirety.

1. A wound approximation device, the device comprising a resilient sheetand an opening, wherein the opening is of a sufficient size such that itsurrounds a skin wound and exposes a margin of skin surrounding thewound when the resilient sheet in a stretched form is placed against theskin, and wherein a portion of the resilient sheet adjacent to theopening and opposite to a side of the resilient sheet to be placedagainst the skin comprises a substance which does not form a strong bondwith a cyanoacrylate wound-sealing adhesive used to seal the wound. 2.The wound approximation device of claim 1, wherein the resilient sheetcomprises an elastomer.
 3. The wound approximation device of claim 1,wherein the resilient sheet comprises a vinyl sheet.
 4. The woundapproximation device of claim 1, wherein the resilient sheet comprises aurethane sheet.
 5. The wound approximation device of claim 1, whereinthe portion of the resilient sheet adjacent to the opening and oppositeto a side of the resilient sheet to be placed against the skin comprisesa vinyl.
 6. The wound approximation device of claim 1, wherein theportion of the resilient sheet adjacent to the opening and opposite to aside of the resilient sheet to be placed against the skin comprises aurethane.
 7. The wound approximation device of claim 1, wherein theportion of the resilient sheet to be placed against the skin comprises abacking adhesive.
 8. The wound approximation device of claim 1, whereinthe backing adhesive comprises a pressure sensitive adhesive.
 9. Thewound approximation device of claim 8, wherein the pressure sensitiveadhesive comprises a butyl acrylate.
 10. A method of sealing a wound,the method comprising the steps of: providing a wound approximationdevice, the device comprising a resilient sheet and an opening, whereina portion of the resilient sheet adjacent to the opening comprises asubstance which does not form a strong bond with a cyanoacrylatewound-sealing adhesive; applying tension to the resilient sheet wherebythe opening is enlarged to a sufficient size such that it may surround askin wound and expose a margin of skin surrounding the wound; pressingthe resilient sheet under tension against the skin to form a bond to theskin, such that the opening surrounds the skin wound and exposes amargin of skin surrounding the wound; releasing the tension in theresilient sheet, whereby the wound is approximated; applying acyanoacrylate wound-sealing adhesive to the approximated wound; andremoving the wound approximation device from the skin, whereby theapproximated wound is sealed.
 11. The method of claim 10, wherein thecyanoacrylate wound-sealing adhesive comprises a butyl cyanoacrylateadhesive.
 12. The method of claim 10, wherein the cyanoacrylatewound-sealing adhesive comprises a octyl cyanoacrylate adhesive.
 13. Themethod of claim 10, wherein the substance which does not form a strongbond with a cyanoacrylate wound-sealing adhesive comprises a vinyl. 14.The method of claim 10, wherein the substance which does not form astrong bond with a cyanoacrylate wound-sealing adhesive comprises aurethane.
 15. The method of claim 10, wherein a portion of the resilientsheet to be placed against the skin comprises a backing adhesive. 16.The method of claim 10, further comprising the step of: debriding theapproximated wound.
 17. The method of claim 10, further comprising thestep of: irrigating the approximated wound.
 18. The method of claim 10,further comprising the step of: disinfecting the approximated wound. 19.The method of claim 10, further comprising the step of: suturing theapproximated wound.
 20. The method of claim 10, further comprising thestep of: stapling the approximated wound.